03-09-2012, 12:23 PM
Efficient Sintering Equipment for the Production of Engineering Ceramics
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Introduction
In ceramic technology, the process
step “sintering” effects the consolidation
of powdered material, generating
a solid body with properties that are
influenced significantly by this process
step. Hence the product quality is
affected by sintering to a large extent.
But in most cases sintering is also the
process step with the highest energy
consumption in the value-added chain
[1]. It contributes substantially to the
fact that a major part (approx. 68 %!)
of energy consumed in industry is used
for processing heat [2]. Moreover the
technology required for sintering is
frequently complex and expensive,
especially in the field of engineering
ceramics. These brief considerations
already indicate the huge relevance of
the efficient design of the process step
“sintering”. But what is “efficient sintering”?
Efficient Sintering –
Influencing Factors
According to the encyclopaedic definition
“efficiency in general de-scribes
the extent to which time or effort is
well used for the intended task or purpose.”
Mathematically this is equivalent
to the ratio of outcome and effort.
“Outcome” in this context is the productivity
of a sintering facility, which is
influenced among other things mainly
by the following factors:
• Batch size (useful capacity of the furnace)
• Cycle time
• Feed time
• Availability rate
• Shift operation
• Scrap rate.
With regard to the “effort”, it is not
sufficient to consider just the energy
consumption (“energy efficiency”),
although this is one of the most important
aspects. Instead an integrated
view of effort is becoming increasingly
accepted (TCO = Total Cost of Ownership
Downsizing vs. Upscaling
A core consideration in the design of
sintering facilities is the realization of
the required productivity. Here it is
often not advisable to try to reach the
required productivity with the use of
one single, big sintering furnace. It is
often much better to split production
between more than one, identical
small-size furnaces operated parallel
(“downsizing”). Small furnaces have
lower electrical connection power as
well as shorter cycle times, which
increase productivity compared with a
single big furnace and benefits product
quality in many cases. Furthermore,
the potential downtime of just
one of several smaller furnaces is much
less significant. If more than one furnace
is operated, personnel, electricity,
cooling water, service intervals etc.
can be kept relatively uniform by offsetting
the individual cycles appropriately,
resulting in a “quasi-continuous
operating mode”.